Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative mat...Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.展开更多
Underwater vehicles are being emphasized as highly integrated and intelligent devices for a significant number of oceanic operations. However, their precise operation is usually hindered by disturbances from a tether ...Underwater vehicles are being emphasized as highly integrated and intelligent devices for a significant number of oceanic operations. However, their precise operation is usually hindered by disturbances from a tether or manipulator because their propellers are unable to realize a stable suspension. A dynamic multi-body model-based adaptive controller was designed to allow the controller of the vehicle to observe and compensate for disturbances from a tether or manipulator. Disturbances, including those from a tether or manipulator, are deduced for the observation of the controller. An analysis of a tether disturbance covers the conditions of the surface, the underwater area, and the vehicle end point. Interactions between the vehicle and manipulator are mainly composed of coupling forces and restoring moments.To verify the robustness of the controller, path-following experiments on a streamlined autonomous underwater vehicle experiencing various disturbances were conducted in Song Hua Lake in China. Furthermore,path-following experiments for a tethered open frame remote operated vehicle were verified for accurate cruising with a controller and an observer, and vehicle and manipulator coordinate motion control during the simulation and experiments verified the effectiveness of the controller and observer for underwater operation. This study provides instructions for the control of an underwater vehicle experiencing disturbances from a tether or manipulator.展开更多
The objective of the paper is to compute the optimal burn-out conditions and control requirements that would result in maximum down-range/cross-range performance of a waverider type hypersonic boost-glide(HBG) vehicle...The objective of the paper is to compute the optimal burn-out conditions and control requirements that would result in maximum down-range/cross-range performance of a waverider type hypersonic boost-glide(HBG) vehicle within the medium and intermediate ranges,and compare its performance with the performances of wing-body and lifting-body vehicles vis-a-vis the g-load and the integrated heat load experienced by vehicles for the medium-sized launch vehicle under study.Trajectory optimization studies were carried out by considering the heat rate and dynamic pressure constraints.The trajectory optimization problem is modeled as a nonlinear,multiphase,constraint optimal control problem and is solved using a hp-adaptive pseudospectral method.Detail modeling aspects of mass,aerodynamics and aerothermodynamics for the launch and glide vehicles have been discussed.It was found that the optimal burn-out angles for waverider and wing-body configurations are approximately 5° and 14.8°,respectively,for maximum down-range performance under the constraint heat rate environment.The down-range and cross-range performance of HBG waverider configuration is nearly 1.3 and 2 times that of wing-body configuration respectively.The integrated heat load experienced by the HBG waverider was found to be approximately an order of magnitude higher than that of a lifting-body configuration and 5 times that of a wing-body configuration.The footprints and corresponding heat loads and control requirements for the three types of glide vehicles are discussed for the medium range launch vehicle under consideration.展开更多
In this paper new matrices of the Cayley-Klein parameters are used to represent composition of several consecutive finite rotations of rigid body. The general commutative rules of multiplication for these matrices is ...In this paper new matrices of the Cayley-Klein parameters are used to represent composition of several consecutive finite rotations of rigid body. The general commutative rules of multiplication for these matrices is obtained. Furthermore, by using these matrices it is convenient to prove the theorem on finite rotation of rigid body. The result obtained in this paper is concise and easy to remember, and can be used to calculate vehicle attitude.展开更多
基于MATLAB矢量化的物质点法(material point method,MPM)框架,分析车身前防撞梁的碰撞冲击问题。MPM在每一迭代步将物理参数在物质点和背景网格间相互映射,使用MATLAB矢量化框架可以使用户在快速入门的同时保证求解效率,其应力更新采...基于MATLAB矢量化的物质点法(material point method,MPM)框架,分析车身前防撞梁的碰撞冲击问题。MPM在每一迭代步将物理参数在物质点和背景网格间相互映射,使用MATLAB矢量化框架可以使用户在快速入门的同时保证求解效率,其应力更新采用车身结构材料的弹塑性本构模型。前防撞梁碰撞冲击数值算例结果表明,MPM可以保证求解精度,同时矢量化技术可以大幅提高求解效率。展开更多
利用裂纹扩展分析方法和质量分类法研究铝合金车体含缺欠焊接结构的疲劳寿命问题。首先,研究IIW:2015的基于Paris定律的裂纹扩展分析的理论基础和BS 7910:2019的基于考虑焊接缺欠质量的S-N曲线的质量分类法的算法原理;其次,归纳总结了这...利用裂纹扩展分析方法和质量分类法研究铝合金车体含缺欠焊接结构的疲劳寿命问题。首先,研究IIW:2015的基于Paris定律的裂纹扩展分析的理论基础和BS 7910:2019的基于考虑焊接缺欠质量的S-N曲线的质量分类法的算法原理;其次,归纳总结了这2种方法进行考虑焊接质量的焊接结构疲劳寿命评估流程;再次,在疲劳载荷作用下,基于BS EN 1999-1-3:2007的名义应力法对某动车组铝合金车体进行疲劳分析,确定车体疲劳关切焊缝部位;最后,分别利用裂纹扩展分析方法和质量分类法对车体关切焊缝侧门下角进行考虑初始裂纹的疲劳寿命评估。结果表明:基于质量分类法的剩余寿命为1.4×106次,基于裂纹扩展分析法的剩余寿命为2.64×106次。展开更多
文摘Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.
基金Supported by National Natural Science Foundation of China(Grant Nos.5129050,51579053,61633009)Major National Science and Technology Project of China(Grant No.2015ZX01041101)Key Basic Research Project of "Shanghai Science and Technology Innovation Plan" of China (Grant No.15JC1403300)
文摘Underwater vehicles are being emphasized as highly integrated and intelligent devices for a significant number of oceanic operations. However, their precise operation is usually hindered by disturbances from a tether or manipulator because their propellers are unable to realize a stable suspension. A dynamic multi-body model-based adaptive controller was designed to allow the controller of the vehicle to observe and compensate for disturbances from a tether or manipulator. Disturbances, including those from a tether or manipulator, are deduced for the observation of the controller. An analysis of a tether disturbance covers the conditions of the surface, the underwater area, and the vehicle end point. Interactions between the vehicle and manipulator are mainly composed of coupling forces and restoring moments.To verify the robustness of the controller, path-following experiments on a streamlined autonomous underwater vehicle experiencing various disturbances were conducted in Song Hua Lake in China. Furthermore,path-following experiments for a tethered open frame remote operated vehicle were verified for accurate cruising with a controller and an observer, and vehicle and manipulator coordinate motion control during the simulation and experiments verified the effectiveness of the controller and observer for underwater operation. This study provides instructions for the control of an underwater vehicle experiencing disturbances from a tether or manipulator.
基金the Chinese Scholarship Council for supporting the research
文摘The objective of the paper is to compute the optimal burn-out conditions and control requirements that would result in maximum down-range/cross-range performance of a waverider type hypersonic boost-glide(HBG) vehicle within the medium and intermediate ranges,and compare its performance with the performances of wing-body and lifting-body vehicles vis-a-vis the g-load and the integrated heat load experienced by vehicles for the medium-sized launch vehicle under study.Trajectory optimization studies were carried out by considering the heat rate and dynamic pressure constraints.The trajectory optimization problem is modeled as a nonlinear,multiphase,constraint optimal control problem and is solved using a hp-adaptive pseudospectral method.Detail modeling aspects of mass,aerodynamics and aerothermodynamics for the launch and glide vehicles have been discussed.It was found that the optimal burn-out angles for waverider and wing-body configurations are approximately 5° and 14.8°,respectively,for maximum down-range performance under the constraint heat rate environment.The down-range and cross-range performance of HBG waverider configuration is nearly 1.3 and 2 times that of wing-body configuration respectively.The integrated heat load experienced by the HBG waverider was found to be approximately an order of magnitude higher than that of a lifting-body configuration and 5 times that of a wing-body configuration.The footprints and corresponding heat loads and control requirements for the three types of glide vehicles are discussed for the medium range launch vehicle under consideration.
文摘In this paper new matrices of the Cayley-Klein parameters are used to represent composition of several consecutive finite rotations of rigid body. The general commutative rules of multiplication for these matrices is obtained. Furthermore, by using these matrices it is convenient to prove the theorem on finite rotation of rigid body. The result obtained in this paper is concise and easy to remember, and can be used to calculate vehicle attitude.
文摘基于MATLAB矢量化的物质点法(material point method,MPM)框架,分析车身前防撞梁的碰撞冲击问题。MPM在每一迭代步将物理参数在物质点和背景网格间相互映射,使用MATLAB矢量化框架可以使用户在快速入门的同时保证求解效率,其应力更新采用车身结构材料的弹塑性本构模型。前防撞梁碰撞冲击数值算例结果表明,MPM可以保证求解精度,同时矢量化技术可以大幅提高求解效率。
文摘利用裂纹扩展分析方法和质量分类法研究铝合金车体含缺欠焊接结构的疲劳寿命问题。首先,研究IIW:2015的基于Paris定律的裂纹扩展分析的理论基础和BS 7910:2019的基于考虑焊接缺欠质量的S-N曲线的质量分类法的算法原理;其次,归纳总结了这2种方法进行考虑焊接质量的焊接结构疲劳寿命评估流程;再次,在疲劳载荷作用下,基于BS EN 1999-1-3:2007的名义应力法对某动车组铝合金车体进行疲劳分析,确定车体疲劳关切焊缝部位;最后,分别利用裂纹扩展分析方法和质量分类法对车体关切焊缝侧门下角进行考虑初始裂纹的疲劳寿命评估。结果表明:基于质量分类法的剩余寿命为1.4×106次,基于裂纹扩展分析法的剩余寿命为2.64×106次。
